Energy cell

ABSTRACT

An electric cell having a hermetic pressure seal, and subject to development of high internal gas pressure in the normal operating region, and provided with an auxiliary venting region at atmospheric pressure separated from the operating region with a frangible disc in a separating wall between operating and venting regions with cotton flock in the venting region to retard any high pressure gas and electrolyte injected after fracture of the disc by high pressure in operating region.

atent 1 laleski Jan. 22, 1974 ENERGY CELL 3,318,737 5/1967 Watanabe eta1 136/133 3,355,329 11/1967 Wilke et a1. 136/178 [75] Invent Mm zalesk"Pleasamvne 3,530,496 9/1970 Amano et a]. 136/107 [73] Assignee: P. R.Mallory & Co., Hnc.,

Indianapolis, I d Primary Examiner-Donald L. Walton Filed y 8 1972Attorney, Agent, or FirmRobert Levine [21] Appl. No.: 255;881 [57]ABSTRACT An electric cell having a hermetic pressure seal, and 52 us. c1136/107 136/178 136/179 subject development high internal gas Pressurein [51] Int. Cl. .1 Hillm 1/06 the normal operating region and providedwith an [58] Field of Search 136/107 133, 178 179 177 auxiliary ventingregion at atmospheric pressure sepa rated from the operating region witha frangible disc [56] References Cited in a separating wall betweenoperating and venting regions with cotton flock in the venting region toretard UNITED SirATES PATENTS any high pressure gas and electrolyteinjected after ET fracture of the disc by high pressure in operating re-I e ove 2,482,514 9/1949 Ruben 136/179 3,256,117 6/1966 Howatt et a].136/178 17 Claims, 2 Drawing Figures as 46 14A 1 ENERGY CELL Thisinvention relates to electric energy cells, and is particularly directedto a design and construction to relieve destructive internal pressuresthat may be developed in the cells during operation.

In the mercury type cells, which have been developed for relativelylarge energy capacities, in relation to the An additional problem thatarises, as a by-product of the generation of excessive'pressure withinthe cell, is the resultant tendency of such excessive pressure to causeleakage of the electrolyte from the cell. As a consequence, afterperiodic use, and the resultant breathing of the cell, that is, intakeof external air during rest periods, after periods of activity in thecell, together with expulsions of electrolyte from the cell, uponrecurring high pressures, the cell suffers deterioration and reductionof its operating life, to much less than its normal life should be withthe volume of the cell material originally available in the cellstructure. 7

The object of this invention is to provide a novel and effective celldesign and construction, in which the cell has a usual operatingcompartment, and in accordance with this invention is provided with anauxiliary chamber, into which gases may be diverted when they reachexcessive pressure.

Another object of the invention is to limit movement of any leakingelectrolyte to only such auxiliary chamber, when the internal gasexceeds a predetermined pressure.

Another object of the invention is to provide means in the auxiliarychamber, in the diverted path of the pressure gas and leakingelectrolyte, that will absorb the energy of momentum of the gas and ofthe electrolyte, and thus reduce both to a static condition in theauxiliary chamber.

Another object is to provide the auxiliary chamber in a relativelynon-operative region of the cell, so that the energy of thehigh-pressure gases and of the projected electrolyte may be spent,without creating any ill effects upon the working components of the cellin the normally operating region of the cell.

Another object of the invention, when applied to an electric cellutilizing an electrolyte and having a hermetic seal to and through whichthe electrolyte might move in random paths under pressure of internalgas pressure is to provide means within the cell for establishing aspecific path of movement of the electrolyte, away from such seal, inresponse to excessive internal gas pressure.

Another object of the invention, in connection with an electric cellwhich utilizes an electrolyte, with a hermetic seal representing apossible region for leakage of the electrolyte, is to provide a'zonehaving a controlled path wherein movement of the electrolyte may bedirected away from the seal.

In accordance with this invention, the electriccell is subdivided intotwo regions, (1) the main region, which contains the operative elementsof the cell, such as the anode material, the cathode depolarizermaterial, and an electrolyte, with a suitable absorbent barrier to serveas -a spacer and to provide additional space for the operatingelectrolyte; and (2) the second or auxiliary pressure-relieving region,which is provided to receive some of the gases generated to excessivepressure during operation, and to receive any displaced operatingelectrolyte when the excess pressure gases move into the auxiliaryregion. The two regions are normally isolated from each other and thehigh pressure gases and the electrolyte are normally excluded from theauxiliary pressure-relieving region, and enter that region only when thepressure of the generated gas becomes excessive, to a point that wouldbe injurious to the construction and operation of the components of thecell, if such pressure were maintained or exceeded.

According to this invention, when such excessive pressure is developedin the cell, a suitable transfer passage is opened between the workingregion and the auxiliary region of the cell, to permit the gas at highpressure in the operating region to enter into the auxiliary region,together with an indeterminate quantity of free electrolyte. The excesspressure in the operating region is thus relieved and any electrolytethat may be forced along with such gas movement into the auxiliaryregion of lower pressure, is held static in said auxiliary region.

Normally the two regions are separated by a plastic wall with athin-section disc. At a predetermined pressure in the operating region,the pressure ruptures the disc and opens a window to serve as thetransfer passage.

The cells to which this invention is herein shown applied, are generallyclosed and sealed with a specific hermetic sealing structure to preventleakage, but the excessive pressures, nevertheless, do cause suchleakage.

In accordance with this invention, the thin pressureresponsive disc isdesigned to fracture at a pressure less than the pressure necessary tobreak through the hermetic seal. Thus, selective pressure control isachieved in fracturing the disc and in directing the high pressure gasinto the auxiliary region before the hermetic seal is broken.

To receive the full benefit of this invention, as a further feature ofthe invention, the space in the auxiliary region is originally filled,in manufacture, with a puffed light-weight material such as cottonflock, which serves to reduce the speed and momentum of any highpressure gas and electrolyte that is forced into the auxiliary chamber,and to absorb the energy of momentum. Then, in addition, the electrolyteis immobilized by the cotton, and is held static in such auxiliaryregion, where it can do no harm to other parts of the cell, and,further, the electrolyte is also thus immobilized against leakageout-through usual sealed regions of the cell, as has been the trouble inconventional cells. In a conventional cell structure, a seal becomesunduly stressed in response to the high gas pressures that have beendeveloped during operation, and some leakage of electrolyte frequentlyresults. The cell appears unslightly, and its ability to function may beaffected or unaffected. lts appearance, alone, is not enough to tell itsoperating condition, but its appearance introduces an ambiguity as toits retained ability to function. Thus, leakage may introduce apsychological apparent defect even if the cell is still sound, and sucha cell may be needlessly discarded.

As a final safety feature, the closure seal of the cell may be providedwith a final vent hole of minimum dimension, that would be available incase of extreme necessity, to permit the exit of any gas generated inexcess of any designed and expected quantity, but, serving nevertheless,to hold such ultimate slow leakage gas velocity to a minimum, due to thebarrier effect of the cotton flock, along the controlled path of themovement of such gas to its exit.

In the construction of the cell to provide the main operating region,the usual components of cathode depolarizer material in cylindricalannular form and a concentric cylindrical annular anode, with aseparating absorbent barrier between cathode and anode for theelectrolyte, are all disposed concentrically within a standard typecylindrical container can; and a central chamber concentric along theaxis of the cell is utilized and provided as a longitudinal andgenerally cylindrical auxiliary pressure-reducing space concentricallywithin the operating region. Thus, the operating region is'disposedcircularly within the large arcuate dimensions of the cell, and theauxiliary pressure-reducing safety region is disposed in and along thecentral axial region of the cell, where the volume of the space thuslost to the operating components is a minimum.

Such auxiliary region along the axis is enclosed in and defined by acylindrical enclosure disposed between the operating region and theauxiliary space or pressure-relieving region of the cell, to isolate theoperating region from such pressure-relieving auxiliary region.

The constructions of one modification of a call embodying this inventionis described in the following specification, taken together with theaccompanying drawings, in which FIG. 1 is a vertical sectional view of acell showing the construction features of the invention; and

FIG. 2 is a sectional view of a part of the cell at the top seal, toshow how pressure gas may leak out through a permitted path and afunctionally positioned vent hole.

This invention of cell construction isgenerally based on solving theproblem of preventing leakage of electrolyte from the cell. Such leakageusually occurs in such a way as to create an impression that the cell isdefective, even though the cell may be sound. But the condition of thecell is ambiguous and uncertain, for its required use as a battery. Suchleakage is usually caused by the generation of gases within the cell,that build up pressure to a value sufficient 'to break through theintended hermetic seal, and that thus causes leakage at and in theregion of the hermetic seal.

Within the philosophy of the invention, the internal structure of thecell is made such as to direct any gases under excess pressure into aspace where any electrolyte moving with the gases will be detained andconfined within the cell and prevented from moving towards the usualhermetic seal. At the same time, the gases under excess pressure will beguided into said space representing an extended path through which thegases must travel before being vented through a final vent hole providedfor that purpose. Thus, no electrolyte is leaked to cast doubt orambiguity upon the effectiveness or validity of the cell. At the sametime, the reduction of the excessive pressures by relief within the cellstructure, prevents damage to the elements of the cell which may besusceptible to excessive pressures.

As shown in FIG. 1 of the drawings, a cell 10 comprises: a container can12 generally formed of nickel plated sheet steel; an annular cathodedopolarizer material structure 14 closely fitting into can 12 with goodelectrical contact; a cylindrical lining 16 in the cathode depolarizerserving as an absorbent barrier to accept a charge of liquidelectrolyte; a quantity of anode material 18 which may be in powder orslurry form; and an anode structure 20 consisting of a cylindrical fonnhaving a metallic cylinder 22 and a confined concentric plastic cylindercontainer 24 provided with an integrally formed head element to serve asa grommet seal for the ultimate sealing of the cell; and a cap seal disc26 of nickel plated steel for sealing the container can i 12 with saidintegrally formed head element as a grommet seal.

In the anode structure 20, the metallic cylinder 22 and the plasticcylinder 24.are disposed to define a central auxiliary chamber 30 whichis concentrically disposed in, but normally isolated and separated fromthe operating chamber 35. That operating chamber 35 is occupied by thedepolarizer material, the absorbent barrier and the anode material orpowder. The auxiliary space 30, along the axis, is occupied by the anodestructure 20 including the two cylinders 22 and 24. The anode structure20 is electrically connected to its outer cell terminal 26 that servesas the sealing disc for the cell.

During the normal conditions and normal operation of the cell, any gaseswhich are generated by the interaction of the anode and the cathodematerials will be confined to the operating chamber 35 by the structuraldesign of the cell.

The container can 12 is closed at the bottom and is provided with anauxiliary co-axially extending closed hollow box 36 to serve as onepolarity terminal for the cell. The upper end of the container can 12surrounds the circular periphery of a peripheral circular flange 24Athat is preferably formed integrally on the cylinder 24, for effectivesealing of the operating compartment when the can 12 is peened over atits upper end 12A to engage and press the end of circular flange 24A asa sealing grommet against the annular flange 26A of the upper contactterminal disc 26. When the cell can 12 is thus peened over to engage theperipheral end flange-24A to seal the cell, the main operating chamber35 is substantially sealed closed to confine all of the operatingmaterials of the anode and the cathode depolarizer material, to thatoperatingchamber between the anode 22 and the cell container can 12.

Upon generation of excessive pressure due to the generation of theinternal gases in the operating chamber 35, proper relief of thepressure is necessary to prevent rupture and injury to the cell. Toprovide such pressure relief, the lower part of the cylindrical wall ofthe plastic cylinder 24, of anode 22, is provided with a thin wallsection 248 to provide a frangible disc area that will be fractured whenthe gas pressure developed in the operating chamber 35 of the cellreaches or exceeds a predetermined pressure considered to be harmful.

That excessive pressure value is selected to be less than the pressurethat could cause leakage at the seal. Thus, relief of excessive pressurein the cell by fracturing the disc to the auxiliary chamber, beforeleakage pressure develops, preservesthe seal and prevents leakage.

The anode structure including the metallic cylinder 22 which engages theanode material 18 is provided with a low-resistance electricalconnection to the outer disc terminal 26. For that purpose, a nail 40,having a rod shaped shank 40A and a head 40B of enlarged diameter,serves as the electrical conductor between the anode cylinder 22 and theouter disc terminal 26. Tight pressure is established between the nailhead 40B and a radially turned-in annular flange 22A of anode cylinder22, by a suitable compression rubber sealing element 42 and a snapring'44 seated in a notched region of the shank 40A under suchconditions as to establish originally, and to maintain, a pressure forceon the radial flange 22A against the head 40B of the nail 40. The upperor outer end of the nail 40 is suitably spot-welded to the'terminal disc26.

In order to take full advantage of the limited space in a cell of thistype that is relatively small in dimension, a space 45 at the bottom ofa cell within the sectional area of the absorbent barrier 16 may befilled with an additional depolarizer pellet 14A, formed on a supportingdisc 46 of nickel plated steel, similar to the can 12, and provided withexpanded fingers 46A to hold the auxiliary depolarizer pellet 14A inplace, and to provide additional electrical contact between theauxiliary depolarizer pellet MA and the can 12.

During operation of the cell, the gases that are formed may generatepressure to a value that may become destructive to the depolarizermaterial and dentrimentally affect the physical contact and electricalengagement between the depolarizer material and the can. Such pressurecould also be effective to move gases up between the can and the grommetseal around the rim 24A, as in conventional structures, which would tendalso to force some of the liquid electrolyte out through the sealingregion out to the outer surface of the terminal disc. The presence ofthe elctrolyte creates a psychological doubt about the effectiveness ofthe cell. Even if the cell were still satisfactory for substantialadditional use, the doubt about its validity could lead to its prematurediscard and unnecessary replacement by another cell.

In accordance with the present invention, the gas under excess pressureis controlled to move along a preselected path, rather than in a randompath which the high pressure gas might find most conveniently available.In order to compel such high pressure gas to move in a predeterminedpath, where some control maybe exercised on the gas and on any attendantelectrolyte, the small disc area 248 is located at the bottom of theanode structure and is made frangible so that it will fracture at apreselected pressure, when that pressure is reached. The frangible'disc24B is thereupon fractured. Thereupon the high pressure in the operatingregion 35 causes the high pressure gas to move into the auxiliarychamber 30, within the anode structure 20, where the pressure isatmospheric, whereupon the high pressure in the operating region 35 isrelieved and reduced.

In order to absorb the energy of momentum of the high pressure gas andof the electrolyte carried by such high pressure gas into the auxiliarychamber 30, a

quantity of loose cotton flock 32 is disposed in the auxiliary chamber30.

Thus, the provision of the safety disc as a valve has served 1. torelieve the high pressure that would otherwise affect the operation ofthe cell; and 2. to reduce the velocity of the high pressure gas tozero; and to stop the movement of the electrolyte. The electrolyte isthen held confined against further movement, and, particularly, is heldfrom moving to the external seal, where the presence of the electrolytecould establish the psychological ambiguity previously referred to, thatwould reflect on the operativeness of the cell. in the absence of theventing chamber 30, a high pressure gas in operating chamber 35 could beeffective to tend to leak past the sealing grommet ring 24A, at corner48, and carry some of the liquid electrolyte with it, to leak under andpast the peened-over end 12A of the enclosure can 12. The safety disc24B fractures before the pressure becomes enough to cause such leakageat corner 48.

With the provision of the additional space within the auxiliary chamberfor the high pressure gas to move into, the total pressure of the gas inthe cell is reduced to a safe value. The generation of further pressurebeyond a further selected value is then prevented by the provision of afinal vent hole 50 which is in communication with the upper end of theauxiliary chamber 30. This arrangement of the vent hole 50 tocommunicate with the upper end of the venting chamber 30, whilerequiring any excess gas from the operating chamber 35 to enter at thebottom of the venting chamber 30, assures that the cotton flock in theauxiliary chamber will provide the maximum retarding effect on both theexcess pressure gas, and any electrolyte carried by the gas.

When the pressure again accumulates, and is present in the auxiliarychamber 30, such pressure can be effected to force gas out past thecorner or region 52 at the upper end or comer of the flange ring 2413 atthe top end of the plastic cylinder 24. Thence the gas can move to thefinal vent hole 50 to relieve the pressure in the cell, as in FIG. 2.

Thus, by means of the simple provision of the internal auxiliary chamberwithin the cell, and the disposition of the frangible disc to guide highpressure gas into the re lief chamber at its bottom end, at a maximumdistance from the sealed end of the cell, any electrolyte that,

might otherwise be moved by high pressure gas to the sealed end of thecell, is kept within the cell limits and prevented from leaking to theoutside to create a false I or ambiguous impression of the lack ofintegrity of the cell.

The invention is not limited to the designed construction of the cell asshown, but may be variously applied according to the designed structureof any cell in which the invention may be utilized, within the spiritand scope of the invention, as set forth in the claims.

What is claimed is:

l. An electric cell comprising:

a cup-shaped container can;

a top closure for said container can, said top closure including ananode terminal assembly;

a space within said container defining an operating region, saidoperating region comprising an annular region along themajor length ofthe radius of said container, said operating region containing activecell components including a cylindrical annular cathode depolarizingmaterial in electrical contact with the container, a concentriccylindrical anode spaced from said cathode material by a separatingabsorbent barrier, and a charge of electrolyte within said operatingregion;

means defining an auxiliary space axially along a minimum innerdimension of the radius, said auxiliary space separated from saidoperating region; and

means constituting a safety rupturable divider between said operatingregion and said auxiliary space, to enable said auxiliary space to serveas a venting region to receive generated gases or electrolyte, if andwhen pressure in said operating region becomes excessive.

2. An electric cell, as in claim 1, in which a material is disposed insaid auxiliary space to retard and slow-down any gas volume driven intosaid auxiliary space under pressure from said defined space.

3. An electric cell, as in claim 1, in which a barrier material isdisposed in said auxiliary space to immobilize any electrolyte forcedinto said auxiliary space when said safety divider ruptures.

4. A electric cell, as in claim 1, in which said auxiliaryspace-defining means is an elongated cylindrical cup disposed co-axiallyand concentrically within the cell.

5. An electric cell, as in claim 4, in which said auxiliaryspace-defining means also embodies said means that constitute the safetyrupturable divider.

6. An electric cell, as in claim 1, in which said container can isrelatively cup-shaped with its top end initially open;

a metallic cap is disposed at and physically joined to the open end ofsaid container can and electrically insulated therefrom, to close andseal said can;

and means supporting said auxiliary space-defining means from saidmetallic cap.

7. An electric cell, as in claim 6, in which said means for supportingsaid auxiliary spacedefining means consists of an elongated linearmetallic element.

8. An electric cell, as in claim 7, in which said linear metallicelement is axially disposed within said cell;

and an anode contact element is disposed to engage and support the anodematerial in operative position in said cell.

9. An electric cell, as in claim 1, in which said anode terminalassembly consists of a metal disc to serve as an end terminal for thecell, a nail welded coaxially to said disc and having an axiallydepending shank with a head on its bottom end, a hollow cylindricalmetallic cup resting coaxially on said nail head and electricallyconnected thereto, a hollow cylindrical insulating cup resting withinsaid metallic cup, and a snap ring for engaging the nail shank to lockthe insulating cup and the metallic cup against the nail head. 10. Anelectric cell, as in claim 9, in which said insulating cup has a smallsection of its wall thinned to be rupturable when the gas pressurewithin the cell reaches or exceeds a predetermined value. 11. Anelectric cell, as in claim 9, in which the anode material of the cellsurrounds said anode terminal assembly and engages said cylindricalmetallic cup which serves as a current collector to said nail forconduction to said metallic disc as a cell electrode terminal. 1 12. Anelectric cell, as in claim 2, in which said retarding material is acellulose material.

13. An electriccell, as in claim 3, in which said barrier material is acellulose material.

14. An electric cell, as in claim 13, in which said auxiliary space isarranged and disposed to have a passage of maximum dimension in aspecific direction, and said passage at its forward end communicateswith space outside the cell through a small vent hole; and saidrupturable divider is positioned at the back or upstream end of saidpath so the retarding material is effective along its whole length inthe auxiliary space to slow down and depress the pressured gas forcedinto said auxiliary space. 15. An electric cell, as in claim 1, in whichmeans are provided to cooperate with said rupturable divider toestablish a pressure gradient in a predetermined path through said cell,with means disposed along said path to control gas pressure andelectrolyte movement injected into said path through said rupturabledivider. 16. An electric cell, as in claim 12, in which said retardingmaterial is cotton.

17. An electric cell, as in claim 13, in which said barri sr a risspite!!-

2. An electric cell, as in claim 1, in which a material is disposed insaid auxiliary space to retard and slow-down any gas volume driven intosaid auxiliary space under pressure from said defined space.
 3. Anelectric cell, as in claim 1, in which a barrier material is disposed insaid auxiliary space to immobilize any electrolyte forced into saidauxiliary space when said safety divider ruptures.
 4. A electric cell,as in claim 1, in which said auxiliary space-defining means is anelongated cylindrical cup disposed co-axially and concentrically withinthe cell.
 5. An electric cell, as in claim 4, in which said auxiliaryspace-defining means also embodies said means that constitute the safetyrupturable divider.
 6. An electric cell, as in claim 1, in which saidcontainer can is relatively cup-shaped with its top end initially open;a metallic cap is disposed at and physically joined to the open end ofsaid container can and electrically insulated therefrom, to close andseal said can; and means supporting said auxiliary space-defining meansfrom said metallic cap.
 7. An electric cell, as in claim 6, in whichsaid means for supporting said auxiliary space-defining means consistsof an elongated linear metallic element.
 8. An electric cell, as inclaim 7, in which said linear metallic element is axially disposedwithin said cell; and an anode contact element is disposed to engage andsupport the anode material in operative position in said cell.
 9. Anelectric cell, as in claim 1, in which said anode terminal assemblyconsists of a metal disc to serve as an end terminal for the cell, anail welded coaxially to said disc and having an axially depending shankwith a head on its bottom end, a hollow cylindrical metallic cup restingCoaxially on said nail head and electrically connected thereto, a hollowcylindrical insulating cup resting within said metallic cup, and a snapring for engaging the nail shank to lock the insulating cup and themetallic cup against the nail head.
 10. An electric cell, as in claim 9,in which said insulating cup has a small section of its wall thinned tobe rupturable when the gas pressure within the cell reaches or exceeds apredetermined value.
 11. An electric cell, as in claim 9, in which theanode material of the cell surrounds said anode terminal assembly andengages said cylindrical metallic cup which serves as a currentcollector to said nail for conduction to said metallic disc as a cellelectrode terminal.
 12. An electric cell, as in claim 2, in which saidretarding material is a cellulose material.
 13. An electric cell, as inclaim 3, in which said barrier material is a cellulose material.
 14. Anelectric cell, as in claim 13, in which said auxiliary space is arrangedand disposed to have a passage of maximum dimension in a specificdirection, and said passage at its forward end communicates with spaceoutside the cell through a small vent hole; and said rupturable divideris positioned at the back or upstream end of said path so the retardingmaterial is effective along its whole length in the auxiliary space toslow down and depress the pressured gas forced into said auxiliaryspace.
 15. An electric cell, as in claim 1, in which means are providedto cooperate with said rupturable divider to establish a pressuregradient in a predetermined path through said cell, with means disposedalong said path to control gas pressure and electrolyte movementinjected into said path through said rupturable divider.
 16. An electriccell, as in claim 12, in which said retarding material is cotton.
 17. Anelectric cell, as in claim 13, in which said barrier material is cotton.